The invention relates to ink jet printers and in particular to methods for assembling ink jet pen components in order to maintain alignment of the components during assembly thereof.
Ink jet printers are continually undergoing design changes to improve the speed and print quality produced by such printers in order to provide printed images which have the appearance of laser printed media. One important advantage of ink jet printers over that of laser printers is that multi-color images may be produced relatively less expensively than with laser printers. Multicolor images are produced by depositing dots of different colors in precise patterns on the print media. One of the difficulties associated with multicolor printing is that the printheads of the individual ink jet pens used to produce the images must be aligned with each other so that the dot placement errors or minimized. Exact alignment of all components during the assembly of an ink jet pen is extremely difficult to achieve. Even if the parts are initially aligned, it is difficult to maintain the alignment throughout the manufacturing process without the use of costly jigs. Even with elaborate alignment equipment, because of the size of the parts, extremely small alignment errors may have a major impact on the performance of the pens in a printer.
The manufacture of a multi-color ink jet is typically a multi-step process. The most common multicolor printer uses individual ink jet pens for each color of ink. The components of the pens including the printheads are aligned and assembled with respect to their pen bodies. The individual pens are then attached to a carriage in side by side relationship. Once the pens are attached to the carriage, the pens may be individually adjusted to provide the desired alignment between the different pen colors. The components of each of the pens are aligned with respect to reference marks on the pen bodies and alignment between the individual color pens is conducted after all of the components of the pens are assembled and attached to the carriage. A disadvantage of this method for aligning the ink jet pens is that multiple alignment steps are required for the individual pens and there is a possibility that misalignment may occur due to wear or damage thereby requiring another costly alignment step.
It is difficult to produce multicolor pens having two or more printheads attached to the same ink jet pen body because of the need to maintain component alignment until all of the adhesive materials used for attaching parts to the pen body are cured. There is a need therefore for manufacturing techniques which are helpful for improving the alignment between component parts of an ink jet pen.
With regard to the foregoing, the invention provides a method for attaching a semiconductor chip to an ink jet pen body which includes dispensing a first adhesive having a cure time greater than about 15 minutes in a predetermined pattern in one or more chip pockets of an ink jet pen body, dispensing beads containing a second adhesive in two or more discrete locations around an inside perimeter of each chip pocket. The second adhesive preferably has a substantially shorter cure time than the first adhesive. A semiconductor chip having chip edges is attached in each of the chip pockets to the second adhesive and the first adhesive is cured using heat or radiation.
In another aspect the invention provides a method for assembling a multi-color ink jet pen which includes providing an ink jet pen body containing two or more semiconductor chip pockets, dispensing a die attach adhesive in a predetermined pattern in each of the chip pockets, the die attach adhesive having a cure time greater than about 15 minutes, dispensing beads containing a second adhesive in two or more discrete locations around an inside perimeter of each chip pocket adjacent the die attach adhesive, the second adhesive having a cure time substantially shorter than the cure time of the die attach adhesive, attaching a semiconductor chip having chip edges in each of the chip pockets to the second adhesive, the semiconductor chips being attached to flexible circuits or TAB circuits, curing the second adhesive to hold the chips in a predetermined alignment, curing the first adhesive using heat or radiation, attaching the flexible circuits or TAB circuits to the ink jet pen body and attaching one or more removable cartridges containing ink to the pen body.
An advantage of the methods of the invention is that the second adhesive is effective to hold the individual semiconductor chips of a multicolor ink jet pen in alignment with respect to one another until the die attach adhesive is cured. Another advantage is that at least one of the adhesives may flow during the bonding and/or curing step to protect the edges of the semiconductor chips while the chips remain fixedly bonded to the ink jet pen body. The process also enables the chips to be aligned to each other at the same time the chips are bonded to the ink jet pen body thereby eliminating a separate step for aligning the chips to one another.